Public bug reported: Everytime /usr/share/mdadm/checkarray RAID consistency check is being executed (started on first sunday of a month by /etc/cron.d/mdadm) on Ubuntu 12.04.4 KVM hypervisor, KVM guests running on the host (Ubuntu/Debian/Scientific linux/Windows ) start to swap, freeze, throwing 'BUG: soft lockup - CPU stuck for..!' errors on the consoles, processes are coredumping on the guests etc. KVM host starts to swap even it has enough memory available and every disk IO demanding operation/process on any guest causes whole environment is affected and unusable (similar situation to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/312163).
RAID check procedure shouldn't cause the KVM guests become unusable. Some of the KVM guests use either qcow2 image storage format (virtio) or RAW disks (LVM, virtio). All KVM guests are affected. Here is the system information: root@kvmserver:~# lsb_release -rd Description: Ubuntu 12.04.4 LTS Release: 12.04 root@kvmserver:~# uname -a Linux kvmserver 3.2.0-59-generic #90-Ubuntu SMP Tue Jan 7 22:43:51 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux HW: Dell PowerEdge R410, 2x Intel Xeon X5650, 64GB RAM, 4x2TB SATA 6.0Gb drives in following RAID configuration: # cat /proc/mdstat Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] md2 : active raid1 sdd3[2] sdc3[0] 1924018648 blocks super 1.2 [2/2] [UU] md1 : active raid1 sdd2[0] sdc2[1] 29296576 blocks [4/2] [UU__] md127 : active raid1 sde1[2] sdf1[0] 2147481446 blocks super 1.2 [2/2] [UU] # free -m total used free shared buffers cached Mem: 64419 56859 7559 0 11671 1185 -/+ buffers/cache: 44002 20416 Swap: 18335 5554 12781 root@kvmserver:~# dpkg -l |egrep 'qemu-kvm|mdadm' ii kvm 1:84+dfsg-0ubuntu16+1.2.0+dfsg+0~12.04~ppa0 dummy transitional package from kvm to qemu-kvm ii mdadm 3.2.5-1ubuntu0.3 tool to administer Linux MD arrays (software RAID) ii qemu 1.2.0+dfsg-0~12.04~ppa0 dummy transitional package from qemu to qemu-kvm ii qemu-kvm 1.2.0+dfsg-0~12.04~ppa0 Full virtualization on supported hardware ** Affects: qemu-kvm (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to qemu-kvm in Ubuntu. https://bugs.launchpad.net/bugs/1339609 Title: md raid resync causing KVM guests overload To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/1339609/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs